An electrically powered trimmer includes a cutting element mounted to the drive shaft of an electric motor, a housing in which the motor is mounted and that is attached to one end of a tube, and a pair of handles at the opposite end of the tube. The cutting element is most often a length of flexible line, though it could also be a blade. The length of line extends from a line head connected to the shaft of the motor. The head is spun rapidly to flail the line against vegetation. Because the line frequently breaks, a supply of flexible line is stored on a spool in the head, the end of the line extending through an opening in the head.
An operator holds the trimmer while standing erect by grasping with one hand a main handle attached to the end the tube that extends upwardly and rearwardly from the housing. Depending on the size of the trimmer, the other hand may grasp an auxiliary handle that can be attached lower down on the tube between the main handle and the housing to provide enhanced control. A trigger located, usually, on the main handle operates a normally off switch that turns the motor on and off.
Usually, power is delivered to the motor by a 120 volt alternating current from a household outlet. A plug or "pigtail" for connection to an extension cord running from the outlet is typically located in the rear of the handle, but is sometimes located elsewhere on the trimmer. The power source alternately is a battery pack placed in the vicinity of the main handle for balance. With either power source, a power wire runs to the electric motor in the housing through the tube to the normally-off trigger switch on the rear handle.
To save space, electric, flexible line trimmers are sometimes packaged and shipped in a "knocked down" or partially disassembled state. The benefits of packing trimmers disassembled are well known and it has been done for many years. Traditionally, to knock down the trimmer, the tube that supports the handles is manufactured in two or more sections that are separated and folded over when placed in a box. In other cases, the tube may be manufactured as a single piece but not attached to the motor housing, the main handle or both to save space.
For safety, the trimmer must be "prewired," as the wire through the tube carries relatively high voltage (120 volt) alternating current. The wire is run through the tube and attached to the electric motor and the power plug and/or trigger switch on the main handle before packaging and shipment. The lower length of the tube is then attached to the housing and the upper length is attached to the rear handle. When the trimmer is taken from the box, the two pieces of the tube are pushed together and secured with bolts. One end of the tube length has a smaller diameter so that it slides into the larger diameter end of the other tube length. An electric trimmer of the general type described is disclosed in U.S. Pat. No. 4,829,675, issued May 16, 1989 to Beihoffer.
Although of considerable benefit in terms of cost of shipping and storage to those who sell trimmers, consumers find assembling a knocked down line trimmer a nuisance and inconvenience. Furthermore, final assembly is not as simple as it may appear. As pointed out in Beihoffer, an extra length of wire is necessary to allow the tube pieces to be pulled apart and folded over and to prevent the end of each piece rubbing against the wire during shipment. The extra length of wire is relatively stiff due to having a size sufficient to carry the AC current. It must be pushed into one or both tube halves, thus making assembly more difficult and tedious. Beihoffer points out that problems may result from a consumer assembling the handle portions in a rough manner or inappropriately forcing the extra wire into one or both handle halves. Furthermore, proper orientation of the upper length of tube length with the lower length is frequently overlooked by first time buyers and is not discovered until after bolts are installed to secure the tube lengths, thus causing frustration and discontent.
Retailers would, naturally, prefer to provide to customers the convenience of a fully assembled trimmer. To maintain the goodwill of their customers, some retailers are willing to assemble the trimmers when they are offered for sale or are sold. However, this may require extra trained personnel. Sometimes they do not have the personnel immediately available or must charge a fee to recover costs, thus inconveniencing the customer.
Beihoffer addresses the problem of the extra length of wire and teaches cutting notches in the ends of the tubes so that the length of the wire may be reduced. However, he provides only a partial solution. Assembly of the tube sections is still required and is inconvenient to the consumer. Thus, the demand for a solution remains.